ASoC: codec: cs42l73: Drop cs42l73.h

There is no in-tree user of "include/sound/cs42l56.h", so move
'struct cs42l73_platform_data ' to cs42l73.c and remove the header file.
And platform data is mostly for legacy platforms that create devices
non using device tree. So drop cs42l73.h to prepare using GPIOD API.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://patch.msgid.link/20250506-csl42x-v3-5-e9496db544c4@nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>